Sci 2144

Lashawone Powell

October 6, 2005

SCI 2144

The three major types of rocks, igneous, sedimentary, and metamorphic rocks are interrelated by a series of natural processes. Igneous rocks form from the cooling and crystallization of hot molten lava and magma. Igneous rocks undergo weathering and erosion to form sediments. Igneous rock can form from magma being brought to the surface by volcanic eruption or it can form beneath the surface. Sediments are deposited and lithified by compaction and cementation to form sedimentary rocks. Unconsolidated sediment is the precursor of sedimentary rock. Sedimentary rock becomes buried by additional sedimentary deposition, and when they are deep within the Earth, they are subjected to heat and pressure which causes them to become metamorphic rocks. With further burial and heating, the metamorphic rocks begin to melt. When heat and pressure below the Earth's surface become high enough, metamorphic rock is formed. Partially molten metamorphic rocks are known as migmatite. As melting proceeds with increasing temperatures and depths of burial, eventually the rock becomes molten and becomes magma, which cools and crystallizes to form plutonic igneous rock, or which is erupted onto the Earth's surface as lava, and cools and